The present invention relates generally to the field of implantable (or implanted) medical devices, and more particularly to uplink and downlink telemetry between an implantable medical device (IMD) telemetry transceiver and an external medical device (EMD) telemetry transceiver.
At present, a wide variety of IMDs are commercially released or proposed for clinical implantation that are programmable in a variety of operating modes and are interrogatable using RF telemetry transmissions between the IMD and an externally located EMD. The terms xe2x80x9ctelemeterxe2x80x9d, xe2x80x9ctelemetry transmissionxe2x80x9d and the like are intended to embrace any action and manner of communicating and conveying patient data and downlink telemetry data between the IMD and any type of EMD in the uplink and downlink telemetry directions.
Typically, certain therapy delivery and monitoring operational modes and parameters of the IMD are altered temporarily or chronically in a non-invasive (i.e. non-surgical) manner using downlink telemetry transmission from an EMD of programming and interrogation commands or downlink messages herein also referred to as xe2x80x9cdownlink telemetry dataxe2x80x9d. Moreover, a wide variety of real time and stored physiologic data as well as non-physiologic, IMD related, data or previously stored implant data (referred to collectively herein as xe2x80x9cpatient dataxe2x80x9d) composed into uplink messages and are uplink telemetered by the IMD to the EMD in response to a downlink telemetered interrogation command that is received by the IMD transceiver.
The EMD is typically characterized as a full function or limited function xe2x80x9cprogrammerxe2x80x9d. The full function programmers are implemented with a full range of programming and interrogation capabilities and are intended for use by a physician or other health care provider to communicate with the EMD. In certain instances, patients are provided with limited function programmers that typically have a limited range of programming functions and are intended for use by the patient to downlink telemeter a command to the IMD to deliver a therapy or change a therapy and/or to store physiologic data when the patient experiences particular symptoms.
A wide variety of IMDs have been developed for use in the human body to monitor the patient""s condition and/or to treat a patients underlying disease state. Such IMDs include implantable cardiac pacemakers, cardioverter/defibrillators, cardiomyostimulators, pacemaker/cardioverter/defibrillators, drug delivery systems, cardiac and other physiologic monitors, electrical stimulators including nerve and muscle stimulators, deep brain stimulators, cochlear implants, and heart assist IMDs or pumps, etc.
Most of these IMDs are used in conjunction with the above-described EMDs that control the operation of the IMDs and receive information from the IMDs. Examples of programmable implantable pacemakers include U.S. Pat. No. 5,456,692, issued to Smith et al., U.S. Pat. No. 5,843,138, issued to Evers, U.S. Pat. No. 5,372,607, issued to Stone et al., U.S. Pat. No. 5,843,139, issued to Goedeke et al., U.S. Pat. No. 4,601,291, issued to Boute et al., U.S. Pat. No. 5,693,076, issued to Kaemmerer, et al., U.S. Pat. No. 5,752,977, issued to Grevious et al., U.S. Pat. No. 5,354,319 issued to Wyborny et al. and U.S. Pat. No. 5,107,833, issued to Barsness et al. Examples of the various other types of programmable IMDs listed above include U.S. Pat. No. 5,342,408, issued to DeCoriolis et al., U.S. Pat. No. 5,383,909, issued to Keimel, U.S. Pat. No. 4,146,029, issued to Ellinwood, U.S. Pat. No. 4,692,147, issued to Duggan, U.S. Pat. No. 5,662,689, issued to Ellsberry et al, U.S. Pat. No. 5,342,409, issued to Mullett, and U.S. Pat. No. 5,331,966, issued to Bennett et al.
In many of the systems described above, activation of telemetry from the IMD to the associated EMD requires placement of a magnet in physical proximity to the IMD. The same type of magnet may also activate a temporary change in IMD operation. The best-known example of such an operational mode change is the initiation of asynchronous pacing operation in an implantable pacemaker, enabling the patient or the patient""s physician to conveniently determine the present pacing rate. This type of magnetically triggered mode change is also useful in the context of trans-telephonic pacemaker monitoring, allowing the remote monitoring IMD to record a paced electrogram, if desired.
The requirement of magnetic activation of the IMD""s telemetry function or mode change, while serving as a useful safety feature, does have some drawbacks. First, the magnets employed are typically relatively heavy, high strength magnets of a type not typically available other than from the IMD manufacturer, making them inconvenient and expensive to replace in the event they are lost or broken. This does not pose a problem in the context of programming or monitoring the IMD using a programmer which employs a programming head placed in proximity to the patient""s body, as such programming heads typically include a built-in magnet, typically an permanent magnet. However, as programming systems which employ programming antennas which may be remote from the body are developed, for example as disclosed in U.S. Pat. No. 5,113,869, issued to Nappholz et al., U.S. Pat. No. 6,169,925, issued to Villaseca et al., and U.S. Pat. No. 6,167,312, issued to Goedeke, a magnet within the programmer is not workable. Second, placement of the magnet in proper orientation and location with regard to the IMD is sometimes difficult, making the process more cumbersome than might be desirable.
The present invention is directed toward providing a mechanism that provides the functions typically provided by an externally applied magnet and an associated magnetic switch and circuitry within the IMD that overcomes problems as described above and advantageously enables the expansion of functions of a patient programmer or EMD.
An IMD according to the present invention provides a therapy and/or measures physiologic conditions of the patient for use in formulating a therapy and/or for storage in IMD memory for later uplink telemetry transmission. The IMD is provided with an audio receiver such as a microphone and internal associated circuitry capable of demodulating dual tone multiple frequency (DTMF) tones of the type employed in modern touch-tone telephones and recognizing a defined sequence of such DTMF tones. In accordance with a further aspect of the invention, the DTMF tones are emitted by an EMD when the EMD is operated to do so by a user, typically the patient receiving the IMD or a health care provider attending the patient. The IMD responds to or is xe2x80x9cunlockedxe2x80x9d by a defined sequence of DTMF tones emitted by the EMD and initiates uplink telemetry transmission or changes an IMD operational mode as was previously accomplished by means of the applied magnetic field.
In one method of the present invention, the patient causes the EMD to emit encoded dual tone multiple frequency (DTMF) tones that are detected by an audio receiver of the IMD to enable uplink and downlink telemetry transmissions in a telemetry or communication session or to alter an IMD operation. When a communication session is started, the patient formulates a message via a message entry mechanism of the EMD that communicates an instruction or query to the IMD. The downlink message is optionally displayed by an EMD display as it is composed by the user and is then downlink telemetered to the IMD. A responsive uplink message from the IMD is uplink telemetered, received by the EMD telemetry transceiver, stored in EMD memory and displayed by EMD display.
The EMD optionally includes a DSVD/modem module for either connection to a telephone line or a cellular telephone receiver in a variety of ways that can provide two-way voice communication between the patient and a remote care provider as well as transmission of uplink telemetered IMD and patient data to a remote EMD.
The IMD may further include an audio tone generator for generating a tone or series of tones indicative of operation or status of the IMD that can be heard by the patient or received and displayed by the IMD. The DTMF tones can also be employed to alter an IMD operation.
This summary of the invention and the objects, advantages and features thereof have been presented here simply to point out some of the ways that the invention overcomes difficulties presented in the prior art and to distinguish the invention from the prior art and is not intended to operate in any manner as a limitation on the interpretation of claims that are presented initially in the patent application and that are ultimately granted.